In a PON (Passive Optical Network) system, data signals having different transmission rates can be time-division multiplexed. For example, in Non Patent Literature 1 mentioned below, the standard for a 10G-EPON (Ethernet® PON) that realizes a transmission rate of 10.3 Gbps is specified so as to be coexistent with a GE-PON having a transmission rate of 1.25 Gbps.
There have been considered various techniques for data identification and reproduction of a signal in which data signals having different transmission rates are time-division multiplexed. Patent Literature 1 mentioned below discloses a technique regarding a multi-rate receiver that performs data identification and reproduction by performing oversampling using a sampling clock having a frequency of at least m times (m≧2) as high as a desired transmission rate of a plurality of transmission rates (hereinafter, “multi-rate”) of a received signal, and selecting reproduction data.